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A reflex arc, then, is the pathway followed by nerves which (a.) carry sensory information from the receptor to the spinal cord, and then (b.) carry the response generated by the spinal cord to effector organs during a reflex action. The pathway taken by the nerve impulse to accomplish a reflex action is called the reflex arc.
For example, if the intended movement direction is associated with stretch of the spindle-bearing muscle, Ia afferent and stretch reflex sensitivity from this muscle is reduced. Gamma fusimotor control therefore allows for the independent preparatory tuning of muscle stiffness according to task goals.
A list of reflexes in humans. Abdominal reflex; Accommodation reflex — coordinated changes in the vergence, lens shape and pupil size when looking at a distant object after a near object. Acoustic reflex or attenuation reflex — contraction of the stapedius and tensor tympani muscles in the middle ear in response to high sound intensities.
A diagram illustrating crossed extensor reflex. The crossed extensor reflex or crossed extensor response or crossed extension reflex is a reflex in which the contralateral limb compensates for loss of support when the ipsilateral limb withdraws from painful stimulus in a withdrawal reflex . [ 1 ]
The stretch reflex (myotatic reflex), or more accurately "muscle stretch reflex", is a muscle contraction in response to stretching a muscle. The function of the reflex is generally thought to be maintaining the muscle at a constant length but the response is often coordinated across multiple muscles and even joints. [ 1 ]
The simplest reflex is initiated by a stimulus, which activates an afferent nerve. The signal is then passed to a response neuron, which generates a response. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called reflex arcs.
In contrast, the tendon reflex operates as a negative feedback mechanism to control muscle tension. Although the tendon reflex is less sensitive than the stretch reflex, it can override the stretch reflex when tension is great, for example, causing a person to drop a very heavy weight. Like the stretch reflex, the tendon reflex is ipsilateral.
A muscle spindle, with γ motor and Ia sensory fibers. A type Ia sensory fiber, or a primary afferent fiber, is a type of afferent nerve fiber. [1] It is the sensory fiber of a stretch receptor called the muscle spindle found in muscles, which constantly monitors the rate at which a muscle stretch changes.